28235等硬件定时器太少，不够用！

楼主可以考虑用PWM模块的timer来当定时器用。

具体的楼主可以参考TI例程包中的Example_2833xEPwmTimerInt例程。

// TI File $Revision: /main/2 $
// Checkin $Date: July 30, 2009 18:44:34 $
//###########################################################################
//
// FILE: Example_2833xEPwmTimerInt.c
//
// TITLE: DSP2833x ePWM Timer Interrupt example.
//
// ASSUMPTIONS:
//
// This program requires the DSP2833x header files.
//
// Other then boot mode configuration, no other hardware configuration
// is required.
//
// As supplied, this project is configured for "boot to SARAM"
// operation. The 2833x Boot Mode table is shown below.
// For information on configuring the boot mode of an eZdsp,
// please refer to the documentation included with the eZdsp,
//
// $Boot_Table:
//
// GPIO87 GPIO86 GPIO85 GPIO84
// XA15 XA14 XA13 XA12
// PU PU PU PU
// ==========================================
// 1 1 1 1 Jump to Flash
// 1 1 1 0 SCI-A boot
// 1 1 0 1 SPI-A boot
// 1 1 0 0 I2C-A boot
// 1 0 1 1 eCAN-A boot
// 1 0 1 0 McBSP-A boot
// 1 0 0 1 Jump to XINTF x16
// 1 0 0 0 Jump to XINTF x32
// 0 1 1 1 Jump to OTP
// 0 1 1 0 Parallel GPIO I/O boot
// 0 1 0 1 Parallel XINTF boot
// 0 1 0 0 Jump to SARAM <- "boot to SARAM"
// 0 0 1 1 Branch to check boot mode
// 0 0 1 0 Boot to flash, bypass ADC cal
// 0 0 0 1 Boot to SARAM, bypass ADC cal
// 0 0 0 0 Boot to SCI-A, bypass ADC cal
// Boot_Table_End$
//
// DESCRIPTION:
//
// This example configures the ePWM Timers and increments
// a counter each time an interrupt is taken.
//
// As supplied:
//
// All ePWM's are initalized. Note that not all devices in the 2833x
// family have all 6 ePWMs.
//
// All timers have the same period
// The timers are started sync'ed
// An interrupt is taken on a zero event for each ePWM timer
//
// ePWM1: takes an interrupt every event
// ePWM2: takes an interrupt every 2nd event
// ePWM3: takes an interrupt every 3rd event
// ePWM4-ePWM6: take an interrupt every event
//
// Thus the Interrupt count for ePWM1, ePWM4-ePWM6 should be equal
// The interrupt count for ePWM2 should be about half that of ePWM1
// and the interrupt count for ePWM3 should be about 1/3 that of ePWM1
//
// Watch Variables:
// EPwm1TimerIntCount
// EPwm2TimerIntCount
// EPwm3TimerIntCount
// EPwm4TimerIntCount
// EPwm5TimerIntCount
// EPwm6TimerIntCount
//
//###########################################################################
// $TI Release: 2833x/2823x Header Files V1.32 $
// $Release Date: June 28, 2010 $
//###########################################################################

#include "DSP28x_Project.h" // Device Headerfile and Examples Include File

// Configure which ePWM timer interrupts are enabled at the PIE level:
// 1 = enabled, 0 = disabled
#define PWM1_INT_ENABLE 1
#define PWM2_INT_ENABLE 1
#define PWM3_INT_ENABLE 1
#define PWM4_INT_ENABLE 1
#define PWM5_INT_ENABLE 1
#define PWM6_INT_ENABLE 1

// Configure the period for each timer
#define PWM1_TIMER_TBPRD 0x1FFF
#define PWM2_TIMER_TBPRD 0x1FFF
#define PWM3_TIMER_TBPRD 0x1FFF
#define PWM4_TIMER_TBPRD 0x1FFF
#define PWM5_TIMER_TBPRD 0x1FFF
#define PWM6_TIMER_TBPRD 0x1FFF

// Prototype statements for functions found within this file.
interrupt void epwm1_timer_isr(void);
interrupt void epwm2_timer_isr(void);
interrupt void epwm3_timer_isr(void);
interrupt void epwm4_timer_isr(void);
interrupt void epwm5_timer_isr(void);
interrupt void epwm6_timer_isr(void);
void InitEPwmTimer(void);

// Global variables used in this example
Uint32 EPwm1TimerIntCount;
Uint32 EPwm2TimerIntCount;
Uint32 EPwm3TimerIntCount;
Uint32 EPwm4TimerIntCount;
Uint32 EPwm5TimerIntCount;
Uint32 EPwm6TimerIntCount;

void main(void)
{
int i;

// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP2833x_SysCtrl.c file.
InitSysCtrl();

// Step 2. Initalize GPIO:
// This example function is found in the DSP2833x_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
// InitGpio(); // Skipped for this example

// Step 3. Clear all interrupts and initialize PIE vector table:
// Disable CPU interrupts
DINT;

// Initialize the PIE control registers to their default state.
// The default state is all PIE interrupts disabled and flags
// are cleared.
// This function is found in the DSP2833x_PieCtrl.c file.
InitPieCtrl();

// Disable CPU interrupts and clear all CPU interrupt flags:
IER = 0x0000;
IFR = 0x0000;

// Initialize the PIE vector table with pointers to the shell Interrupt
// Service Routines (ISR).
// This will populate the entire table, even if the interrupt
// is not used in this example. This is useful for debug purposes.
// The shell ISR routines are found in DSP2833x_DefaultIsr.c.
// This function is found in DSP2833x_PieVect.c.
InitPieVectTable();

// Interrupts that are used in this example are re-mapped to
// ISR functions found within this file.
EALLOW; // This is needed to write to EALLOW protected registers
PieVectTable.EPWM1_INT = &epwm1_timer_isr;
PieVectTable.EPWM2_INT = &epwm2_timer_isr;
PieVectTable.EPWM3_INT = &epwm3_timer_isr;
PieVectTable.EPWM4_INT = &epwm4_timer_isr;
PieVectTable.EPWM5_INT = &epwm5_timer_isr;
PieVectTable.EPWM6_INT = &epwm6_timer_isr;
EDIS; // This is needed to disable write to EALLOW protected registers

// Step 4. Initialize all the Device Peripherals:
// This function is found in DSP2833x_InitPeripherals.c
// InitPeripherals(); // Not required for this example
InitEPwmTimer(); // For this example, only initialize the ePWM Timers

// Step 5. User specific code, enable interrupts:

// Initalize counters:
EPwm1TimerIntCount = 0;
EPwm2TimerIntCount = 0;
EPwm3TimerIntCount = 0;
EPwm4TimerIntCount = 0;
EPwm5TimerIntCount = 0;
EPwm6TimerIntCount = 0;

// Enable CPU INT3 which is connected to EPWM1-6 INT:
IER |= M_INT3;

// Enable EPWM INTn in the PIE: Group 3 interrupt 1-6
PieCtrlRegs.PIEIER3.bit.INTx1 = PWM1_INT_ENABLE;
PieCtrlRegs.PIEIER3.bit.INTx2 = PWM2_INT_ENABLE;
PieCtrlRegs.PIEIER3.bit.INTx3 = PWM3_INT_ENABLE;
PieCtrlRegs.PIEIER3.bit.INTx4 = PWM4_INT_ENABLE;
PieCtrlRegs.PIEIER3.bit.INTx5 = PWM5_INT_ENABLE;
PieCtrlRegs.PIEIER3.bit.INTx6 = PWM6_INT_ENABLE;

// Enable global Interrupts and higher priority real-time debug events:
EINT; // Enable Global interrupt INTM
ERTM; // Enable Global realtime interrupt DBGM

// Step 6. IDLE loop. Just sit and loop forever (optional):
for(;;)
{
asm(" NOP");
for(i=1;i<=10;i++)
{}
}

}

void InitEPwmTimer()
{

EALLOW;
SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 0; // Stop all the TB clocks
EDIS;

// Setup Sync
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Pass through
EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Pass through
EPwm3Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Pass through
EPwm4Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Pass through
EPwm5Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Pass through
EPwm6Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN; // Pass through

// Allow each timer to be sync'ed

EPwm1Regs.TBCTL.bit.PHSEN = TB_ENABLE;
EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE;
EPwm3Regs.TBCTL.bit.PHSEN = TB_ENABLE;
EPwm4Regs.TBCTL.bit.PHSEN = TB_ENABLE;
EPwm5Regs.TBCTL.bit.PHSEN = TB_ENABLE;
EPwm6Regs.TBCTL.bit.PHSEN = TB_ENABLE;

EPwm1Regs.TBPHS.half.TBPHS = 100;
EPwm2Regs.TBPHS.half.TBPHS = 200;
EPwm3Regs.TBPHS.half.TBPHS = 300;
EPwm4Regs.TBPHS.half.TBPHS = 400;
EPwm5Regs.TBPHS.half.TBPHS = 500;
EPwm6Regs.TBPHS.half.TBPHS = 600;

EPwm1Regs.TBPRD = PWM1_TIMER_TBPRD;
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Count up
EPwm1Regs.ETSEL.bit.INTSEL = ET_CTR_ZERO; // Select INT on Zero event
EPwm1Regs.ETSEL.bit.INTEN = PWM1_INT_ENABLE; // Enable INT
EPwm1Regs.ETPS.bit.INTPRD = ET_1ST; // Generate INT on 1st event

EPwm2Regs.TBPRD = PWM2_TIMER_TBPRD;
EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Count up
EPwm2Regs.ETSEL.bit.INTSEL = ET_CTR_ZERO; // Enable INT on Zero event
EPwm2Regs.ETSEL.bit.INTEN = PWM2_INT_ENABLE; // Enable INT
EPwm2Regs.ETPS.bit.INTPRD = ET_2ND; // Generate INT on 2nd event

EPwm3Regs.TBPRD = PWM3_TIMER_TBPRD;
EPwm3Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Count up
EPwm3Regs.ETSEL.bit.INTSEL = ET_CTR_ZERO; // Enable INT on Zero event
EPwm3Regs.ETSEL.bit.INTEN = PWM3_INT_ENABLE; // Enable INT
EPwm3Regs.ETPS.bit.INTPRD = ET_3RD; // Generate INT on 3rd event

EPwm4Regs.TBPRD = PWM4_TIMER_TBPRD;
EPwm4Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Count up
EPwm4Regs.ETSEL.bit.INTSEL = ET_CTR_ZERO; // Enable INT on Zero event
EPwm4Regs.ETSEL.bit.INTEN = PWM4_INT_ENABLE; // Enable INT
EPwm4Regs.ETPS.bit.INTPRD = ET_1ST; // Generate INT on 1st event

EPwm5Regs.TBPRD = PWM5_TIMER_TBPRD;
EPwm5Regs.TBCTL.bit.CTRMODE= TB_COUNT_UP; // Count up
EPwm5Regs.ETSEL.bit.INTSEL = ET_CTR_ZERO; // Enable INT on Zero event
EPwm5Regs.ETSEL.bit.INTEN = PWM5_INT_ENABLE; // Enable INT
EPwm5Regs.ETPS.bit.INTPRD = ET_1ST; // Generate INT on 1st event

EPwm6Regs.TBPRD = PWM6_TIMER_TBPRD;
EPwm6Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Count up
EPwm6Regs.ETSEL.bit.INTSEL = ET_CTR_ZERO; // Enable INT on Zero event
EPwm6Regs.ETSEL.bit.INTEN = PWM6_INT_ENABLE; // Enable INT
EPwm6Regs.ETPS.bit.INTPRD = ET_1ST; // Generate INT on 1st event

EALLOW;
SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 1; // Start all the timers synced
EDIS;

}

// Interrupt routines uses in this example:
interrupt void epwm1_timer_isr(void)
{
EPwm1TimerIntCount++;

// Clear INT flag for this timer
EPwm1Regs.ETCLR.bit.INT = 1;

// Acknowledge this interrupt to receive more interrupts from group 3
PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;
}

interrupt void epwm2_timer_isr(void)
{
EPwm2TimerIntCount++;

// Clear INT flag for this timer
EPwm2Regs.ETCLR.bit.INT = 1;

// Acknowledge this interrupt to receive more interrupts from group 3
PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;
}

interrupt void epwm3_timer_isr(void)
{
EPwm3TimerIntCount++;

// Clear INT flag for this timer
EPwm3Regs.ETCLR.bit.INT = 1;

// Acknowledge this interrupt to receive more interrupts from group 3
PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;
}

interrupt void epwm4_timer_isr(void)
{
EPwm4TimerIntCount++;

// Clear INT flag for this timer
EPwm4Regs.ETCLR.bit.INT = 1;

// Acknowledge this interrupt to receive more interrupts from group 3
PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;
}

interrupt void epwm5_timer_isr(void)
{
EPwm5TimerIntCount++;

// Clear INT flag for this timer
EPwm5Regs.ETCLR.bit.INT = 1;

// Acknowledge this interrupt to receive more interrupts from group 3
PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;
}

interrupt void epwm6_timer_isr(void)
{
EPwm6TimerIntCount++;

// Clear INT flag for this timer
EPwm6Regs.ETCLR.bit.INT = 1;

// Acknowledge this interrupt to receive more interrupts from group 3
PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;
}

//===========================================================================
// No more.
//===========================================================================

是这段代码吗？

是的。